It tends to happen if you make your character weigh too much. I noticed there seems to be a rip in the collar of Blade armour that I hadn't seen before.
blades armor clips tavern clothes (sad face) ancient nord armor some clothes when you run some clothes when you sneak (ancient nord, jester, wolf armor, etc.)
The left hand and shield clip with the sheathed weapon and weapons clips with legs.I think most of these issue may be adjusted by tweaking the animation files and the meshes. I noticed that most high profile custom armor and meshes tend to be clip free. This is not a surprise, though: modders are known to be perfectionists and devote an enormous amount of time to details, something a paid professional cannot afford to do (even with the skills and experience)